Methods of treating surfaces of substrates

ABSTRACT

In one aspect, the invention includes a method of treating a surface of a substrate. A mixture which comprises at least a frozen first material and liquid second material is provided on the surface and moved relative to the substrate. In another aspect, the invention encompasses a method of treating a plurality of substrates. A treating member is provided proximate a first substrate, and an initial layer of frozen material is formed over a surface of the treating member. A surface of the first substrate is treated by moving at least one of the treating member and the first substrate relative to the other of the treating member and the first substrate. After the surface of the first substrate is treated, the initial layer of frozen material is removed from over the surface of the treating member. The treating member is then provided proximate another substrate, and the surface of the other substrate is treated by moving at least one of the treating member and the second substrate relative to the other of the treating member and the second substrate.

TECHNICAL FIELD

[0001] The invention pertains to methods of treating surfaces ofsubstrates, such as, for example, methods of polishing and cleaningsubstrate surfaces. In particular aspects, the invention pertains tomethods of polishing and/or cleaning surfaces of semiconductive materwafers.

BACKGROUND OF THE INVENTION

[0002] It is frequently desired to treat substrate surfaces duringfabrication of semiconductive material wafers. Exemplary processesinclude procedures whereby surfaces of semiconductor substrates arecleaned and/or polished. To aid in interpretation of the claims thatfollow, the terms “semiconductor substrate” and “semiconductivesubstrate” are defined to mean any construction comprisingsemiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” refers to any supporting structure,including, but not limited to, the semiconductive substrates describedabove. An exemplary semiconductive substrate is a wafer ofmonocrystalline silicon.

[0003] Among the methods of polishing a semiconductive material surfaceis chemical-mechanical polishing. Chemical-mechanical polishing isaccomplished by providing a slurry of liquid and solid particulates overa wafer and mechanically abrading the wafer surface with the slurry.(The liquid can comprise, for example, an aqueous solution havingammonium ions therein, and the solid particulates can comprise, forexample, silicon slurry particulates and/or cesium slurry particulates.)The mechanical abrasion can be accomplished by providing a polishing padabove the wafer surface and spinning one or both of the wafer and thepad to cause the wafer surface to be moved relative to the polishingpad. A problem that can occur during polishing of a wafer surface is inremoval of the particulates from over the surface at the termination ofthe polishing process. Particulates that are not removed from over thewafer can cause damage to electrical devices formed over the wafer.

[0004] Several procedures have been developed to assist in cleaningparticulates from a wafer surface. Among the procedures is to flush aliquid over the wafer surface while mechanically agitating the liquidwith a cleaning member. Such cleaning member can comprise, for example,a brush or a polishing pad. The agitation of the liquid can help todislodge particles from the wafer surface. Another method which has beenutilized to clean a wafer surface is to project solid particles againstthe wafer surface. In one application, solid particles of carbon dioxide(CO₂) are ejected against a semiconductive material surface to dislodgeparticles from the surface. An advantage of utilizing solid CO₂ is thatthe material can be sublimed from the semiconductive material surface toenable easy removal of the material.

[0005] It would be desirable to develop alternative methods for cleaningand/or polishing substrates. It would be particularly desirable todevelop alternative methods for polishing and/or cleaning semiconductivematerial substrates, such as, for example, monocrystalline siliconwafers.

SUMMARY OF THE INVENTION

[0006] In one aspect, the invention includes a method of treating asurface of a substrate. A mixture which comprises at least a frozenfirst material and a liquid second material is provided on the surfaceand moved relative to the substrate.

[0007] In another aspect, the invention encompasses a method of treatinga plurality of substrates. A treating member is provided proximate afirst substrate, and an initial layer of frozen material is formed overa surface of the treating member. A surface of the first substrate istreated by moving at least one of the treating member and the firstsubstrate relative to the other of the treating member and the firstsubstrate. After the surface of the first substrate is treated, theinitial layer of frozen material is removed from over the surface of thetreating member. The treating member is then provided proximate anothersubstrate, and the surface of the other substrate is treated by movingat least one of the treating member and the second substrate relative tothe other of the treating member and the second substrate.

[0008] In yet another aspect, the invention encompasses a method oftreating a surface of a semiconductive material wafer. A treating memberhaving a substantially planar surface is provided, and a layer of frozenmaterial is formed over the substantially planar surface. A surface of asemiconductive material wafer is contacted with the layer of frozenmaterial, and at least one of the treating member and the wafer isremoved relative to the other of the treating member and the wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

[0010]FIG. 1 is a diagrammatic view of a substrate surface treatmentapparatus encompassed by the present invention.

[0011]FIG. 2 is a diagrammatic view of another embodiment substratesurface treatment apparatus of the present invention.

[0012]FIG. 3 is a diagrammatic view of yet another embodiment surfacetreatment apparatus of the present invention, shown at a preliminarystep prior to providing a substrate proximate the apparatus.

[0013]FIG. 4 is a view of the FIG. 3 apparatus, shown at a stepsubsequent to that of FIG. 3, and shown having a substrate proximate theapparatus.

[0014]FIG. 5 is a view of the FIG. 3 apparatus shown at a stepsubsequent to that of FIG. 4.

[0015]FIG. 6 is a diagrammatic view of yet another substrate surfacetreatment apparatus encompassed by the present invention.

[0016]FIG. 7 is a diagrammatic view of yet another substrate surfacetreatment apparatus encompassed by the present invention.

[0017]FIG. 8 is a diagrammatic view of yet another substrate surfacetreatment apparatus encompassed by the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] This disclosure of the invention is submitted in furtherance ofthe constitutional purposes of the U.S. Patent Laws “to promote theprogress of science and useful arts” (Article 1, Section 8).

[0019] The invention encompasses methods of treating substrate surfaceswith frozen solids. In particular embodiments, the invention encompassesmethods of cleaning and/or polishing semiconductive material wafersurfaces, such as, for example, methods of cleaning and/or polishingmonocrystalline silicon wafer surfaces. Several different aspects of theinvention are described below with reference to FIGS. 1-8. In oneaspect, a substrate is cleaned and/or polished by freezing a liquid to asurface of a treating device (such as, for example, a roller or platen)and contacting the substrate to be cleaned or polished with the frozenliquid while applying a mechanical action. After the substrate has beenprocessed, the frozen liquid is mechanically removed, melted orvaporized. A new layer of frozen material can then be reapplied to thetreating device prior to processing another substrate with the treatingdevice. In another aspect, a substrate is sprayed or rinsed with amixture comprising a frozen material and a liquid (of the course themixture can comprise materials other than the frozen material and theliquid, such as, for example, silicon slurry particles, ammonium ions,and/or cesium slurry particles). In yet another aspect, a substrate issubmerged within a mixture comprising a frozen material and a liquid,and agitated therein. In yet another aspect, the invention encompasses amethod of cleaning and/or polishing wherein frozen particles areinjected into a cold fluid stream which is subsequently flowed directlyonto a substrate.

[0020] As will become apparent from the embodiments discussed below,several aspects of the invention comprise changing materials from onestate of matter to another, such as, for example, from a solid state ofmatter to a liquid state of matter. Such phase changes can beaccomplished by subjecting the materials to one or both of a change intemperature or a change in pressure.

[0021] A first aspect of the invention is described with reference toFIG. 1, which illustrates a first embodiment cleaning apparatus 10.Apparatus 10 comprises a platen 12 having a layer 14 of frozen materialformed thereon. Layer 14 can comprise, for example, CO₂, or H₂O, and canbe formed by spraying a liquid onto a cooled platen 12. Specifically,platen 12 can be cooled to below a freezing temperature of the materialof layer 14, and layer 14 can be applied to platen 12 as a liquid whichsubsequently freezes to form the frozen layer 14 over platen 12. Anupper surface 15 of layer 14 is referred to as a “treating” surface, assuch will be utilized to treat a substrate surface.

[0022] In the shown embodiment, a liquid layer 16 is formed on treatingsurface 15, and accordingly over frozen material layer 14. Liquid layer16 can comprise the material of layer 14, or can comprise a differentmaterial. Liquid layer 16 can result from surface melting of layer 14,or can be formed by applying a liquid over layer 14. In particularembodiments, layer 16 will comprise a liquid with a lower freezingtemperature than the material of layer 14 such that the material oflayer 16 remains a liquid at temperatures which freeze the material oflayer 14. For instance, layer 16 can comprise glycol in embodimentswherein layer 14 comprises H₂O.

[0023] Apparatus 10 further comprises a carrier 18 configured to receiveand support a substrate. A substrate 20 is shown supported by carrier18. Substrate 20 can comprise, for example, a semiconductive materialwafer, such as, for example, a wafer of monocrystalline silicon. Inoperation, substrate 20 is lowered to contact one or both of frozenlayer 14 and liquid layer 16. Subsequently, at least one of platen 12and substrate 20 is moved relative to the other of platen 12 andsubstrate 20 to cause layer 14 to move relative to a surface 22 ofsubstrate 20.

[0024] In the shown embodiment, cleaning member 12 comprises asubstantially planar surface 24 upon which frozen material layer 14 isformed. Also in the shown embodiment, surface 22 of substrate 20 issubstantially planar. Surface 22 has a peripheral edge 26 extendingaround it. In particular applications, substrate 20 is a wafer having acircular shape. In such embodiments, periphery 26 also comprises acircular shape. In the exemplary shown embodiment, planar surface 24 ofcleaning member 12 extends outwardly beyond peripheral 26 on all sidesof surface 22 of substrate 20. Such enables an entirety of surface 22 tobe uniformly polished when wafer 20 is brought into contact with frozenlayer 14 and moved relative to frozen layer 14.

[0025] Platen 12 can be referred to as a cleaning member. In particularembodiments of the invention, cleaning member 12 can be replaced withother devices besides a platen, such as, for example, a roller.

[0026] It is noted that liquid layer 16 is optional in methods of thepresent invention, but can provide an advantage in removing contaminantsfrom over frozen surface 14. Specifically, treating member 12 and frozenlayer 14 can together be considered a mechanical treating device whichimparts energy to surface 22 of substrate 20. The rigidity of structures12 and 14 enables such structures to impart significant energy tosurface 22, but such rigid structures are poor for carrying contaminantsaway. Liquid 16, however, has preferred qualities for removingcontaminants from between surface 22 and layer 14. Accordingly, in apreferred application of the present invention, treating member 12 andfrozen layer 14 are utilized to impart energy to surface 22, and fluid16 is flowed across surface 14 to continuously remove contaminants frombetween layer 14 and surface 22.

[0027] The method described above with reference to FIG. 1 treatssurface 22, and can be utilized, for example, to polish surface 22and/or to clean particulates from surface 22.

[0028] After surface 22 has been treated, substrate 20 can be removedfrom apparatus 10, and replaced with another substrate which is to betreated. In particular embodiments, treating surface 15 is cleaned priorto providing another substrate within apparatus 10. Such cleaning canremove contaminants from treating surface 15, and accordingly alleviatecross contamination between different wafers treated within apparatus10. The utilization of frozen material 14 can simplify cleaning oftreating surface 15. Specifically, material 14 can be simply melted andremoved from over surface 24 of treating member 12 by, for example,flushing melted material 14 off from surface 12. The melted material 14will carry with it contaminants that had been associated with surface15. Subsequently, a new layer 14 can be frozen on top of treating member12, to form a new, clean, and substantially planar treating surface 15.The melted material of layer 14 can be subjected to a purificationprocess, such as, for example, filtration or distillation, andsubsequently reutilized to form a frozen layer over cleaning member 12.

[0029] Of course other methods, besides melting, can be utilized toremove at least a portion of frozen material 14 from over treatingmember 12. Such other methods include, for example, mechanicallyremoving material of surface 15 from over member 12, by, for example,scraping or chipping. In particular embodiments, only a thin portion offrozen material 14 comprising surface 15 is removed, and the remainingportion of frozen material 14 is utilized in cleaning a subsequent wafersubstrate.

[0030] Another embodiment of the invention is described with referenceto FIG. 2. FIG. 2 illustrates an apparatus 30 configured for treating asurface. Apparatus 30 comprises a treating member 32 which, in the shownembodiment, comprises a polishing pad 34. It is to be understood,however, that treating member 32 can comprise other forms, such as, forexample, a brush.

[0031] Apparatus 30 further comprises a substrate holder 36, which inthe shown embodiment is holding a substrate 38. Substrate 38 cancomprise, for example, a semiconductive material wafer, such as, forexample, a monocrystalline silicon wafer. Substrate 38 comprises asurface 40 which is to be treated. The treatment can comprise, forexample, polishing and/or cleaning of surface 40. A mixture of frozenfirst material 42, and liquid second material 44 is provided on surface40 of substrate 38. The first material of frozen first material 42 andthe second material of liquid material 44 can comprise the samematerial. In aspects in which the frozen material and liquid materialcomprise the same material, the mixture of materials 42 and 44 can bereferred to as a slurry. In one aspect, the frozen material and liquidmaterial can both comprise CO₂. In another aspect, the frozen materialand liquid material can both comprise H₂ 0. In further aspects, thefrozen material and liquid material can both consist essentially of CO₂,or H₂O.

[0032] Liquid material 44 can also differ from solid material 42. Inaspects in which the frozen material and liquid material comprise thedifferent materials, the mixture of materials 42 and 44 can be referredto as a suspension. In such other aspects, the liquid material 44 cancomprise a lower freezing point than the solid material 42. Forinstance, solid material 42 can comprise H₂O, and liquid material 44 cancomprise glycol. Alternatively, liquid material 44 can comprise a higherfreezing point than solid material 42. For instance, liquid material 44can comprise H₂O and solid material 42 can comprise CO₂.

[0033] In embodiments in which liquid material 44 and solid material 42comprise the same material, the mixture of solid material 42 and liquidmaterial 44 can be formed by providing a liquid consisting essentiallyof such material, and cooling the liquid to about a freezing pointtemperature of the material. At such temperature, there will be anequilibrium between a liquid form of the material and a solid form ofthe material.

[0034] In embodiments in which the material of liquid 44 differs fromthe material of solid 42, and in which the material of solid 42 has ahigher freezing point than the material of liquid 44, the mixture ofsolid material 42 and liquid material 44 can be formed by, for example,forming and cooling a liquid blend of the materials that are ultimatelyto be incorporated into solid 42 and liquid 44. Specifically, the liquidblend is cooled to a temperature between the freezing point of thematerial of solid 42 and the freezing point of the material of liquid44. At such temperature, solid 42 will form, and the material of liquid44 will remain liquid. In an exemplary embodiment, the liquid blend willcomprise a blend of liquid H₂O and glycol, and the mixture of solid 42and liquid 44 will be formed by cooling the blend to a temperature belowthe freezing point of water (0° C.) and above the freezing point ofglycol.

[0035] Liquid 44 and frozen solid 42 are provided between substrate 38and treating member 34. Subsequently, member 34 is utilized to move themixture of materials 44 and 42 relative to surface 40 of substrate 38.Such moving can be accomplished by moving one or both of substrate 38and cleaning member 32. The movement of materials 44 and 42 relative tosurface 40 can cause cleaning and/or polishing of surface 40. Forinstance, pad 34 can be utilized to push the mixture of solids 42 andliquid 44 along surface 40. Solids 42 can be utilized to impartmechanical energy to surface 40 for dislodging contaminants from thesurface, or, in particular applications, for polishing the surface, andliquid 44 can be utilized for flushing the dislodged contaminants awayfrom surface 40.

[0036] After the mixture of liquid 44 and solids 42 has been movedrelative to surface 40, such mixture can be removed from the surface.The mixture can be removed by flushing the mixture off from surface 40with additional liquid 44. During or after removal of the mixture fromsurface 40, solids 42 can be melted or sublimed to convert the frozenmaterial from a solid state of matter to another state of matter (i.e.,to a gas if the solid is sublimed, and to a liquid if the solid ismelted). If the solid is melted, a liquid will be formed comprisingmaterials of solids 42 and liquid 44. Such liquid can be a blend ifsolids 42 comprised a different material than that of liquid 44, or cancomprise a single material if solids 42 and liquid 44 comprised commonmaterials. In any event, the liquid formed after melting solids 42 canbe subjected to a purification process, such as, for example, filtrationor distillation. The liquid can then be subjected to conditions whichreform the frozen solids 42 within liquid 44. Such conditions cancomprise, for example, cooling the liquid to a temperature which causesthe material of solids 42 to freeze. After solids 42 are reformed withinliquid 44, the mixture of solids 42 and liquid 44 can be re-utilized toclean and/or polish substrate surfaces.

[0037] Another embodiment of the invention is described with referenceto FIGS. 3-5. Referring to FIG. 3, an apparatus 50 comprises a substratetreating member 52 and a substrate holder 54. Substrate cleaning member52 is shown in the form of a brush, and comprises bristles 56 extendingfrom a rotatable member 58. Rotatable member 58 is configured to rotatein a direction indicated by arrow 60 and to accordingly spin bristles 56relative to a substrate held within holder 54.

[0038] Referring to FIG. 4, a substrate 62 is provided on holder 54 tobe supported by holder 54. Additionally, a layer of frozen material 64is formed over bristles 56, and cleaning member 52 is subsequentlypositioned proximate substrate 62 such that frozen material 64 contactsa surface 66 of substrate 62. In operation, rotatable member 58 isrotated to spin bristles 56 relative to surface 66 and accordingly tobrush surface 66 with frozen material 64. Contaminants on surface 66 aredisplaced by the mechanical action of frozen material 64, resulting incleaning of surface 66.

[0039] Frozen material 64 can comprise, for example, H₂O or CO₂, or canconsist essentially of, for example, H₂O or CO₂. Frozen material 64 canbe formed by providing a liquid over bristles 56 and subsequentlycooling bristles 56 to a temperature below the freezing temperature ofthe liquid. In one aspect, frozen material 64 can be formed on bristles56 by providing a liquid material over substrate surface 66 (i.e.,between the substrate surface and the bristles), cooling the bristles tobelow a freezing temperature of the liquid, and rotating the bristles tofreeze the material onto the bristles.

[0040] After surface 66 is cleaned, frozen material 64 can be removedfrom bristles 56 by melting or subliming material 64, or alternativelyby scraping material 64 from bristles 56. In applications whereinmaterial 64 is scraped from bristles 56, the material can besubsequently melted. Once material 64 is melted, whether directly meltedfrom bristles 56 or scraped from bristles 56 and subsequently melted,such material can be subjected to a purification process, such as, forexample, distillation or filtration, to remove contaminants from themelted material. The purified material can then be re-frozen on acleaning member and utilized again in a process such as that describedwith reference to FIG. 4. Accordingly, in one aspect of the invention,frozen material 64 is utilized to clean a surface of substrate 62 and issubsequently converted from a solid phase to another state of matter.Such other state of matter can comprise, for example, a liquid, which issubsequently purified and then converted back to the solid phase to beutilized for cleaning a surface of another substrate.

[0041] It is noted that substrate 62 can comprise, for example, asemiconductive material wafer fragment, such as, for example, amonocrystalline silicon wafer. It is also noted that a process of thetype described with reference to FIG. 4 can be utilized to clean a waferafter previous processing steps that form particulates on the wafer. Anexemplary process which would form particulates on the wafer ischemical-mechanical polishing. Accordingly, a process of the presentinvention can be utilized to clean a semiconductive material wafer afterthe wafer has been subjected to chemical-mechanical polishingconditions. Further, in applications in which the methodology describedwith reference to FIGS. 3 and 4 is utilized to clean a plurality ofsubstrates, each of the substrates that is cleaned can be subjected tochemical-mechanical polishing conditions before the cleaning.

[0042] A further aspect of the embodiment described with reference toFIGS. 3 and 4 is described with reference to FIG. 5. Specifically, FIG.5 shows that a second frozen material layer 68 can be formed over firstfrozen material layer 64. Second layer 68 can comprise the same materialas first layer 64, or can comprise a different material. An advantage offorming second frozen material layer 68 over first frozen material layer64 is that such can form a clean surface over first frozen materiallayer 64 after the first frozen material layer 64 has been utilized forcleaning a substrate. More specifically, it is recognized that firstfrozen material layer 64 can become contaminated when cleaning asubstrate. Such contaminated first frozen material layer 64 can beundesirable for use in cleaning subsequent substrates, in that thecontamination on first frozen material layer 64 can be transferred tosuch substrates during a cleaning process. One method of addressing suchproblem is to simply remove material 64 and form a new frozen materialover bristles 56. FIG. 5 illustrates an alternative method of addressingthe problem wherein a second frozen layer 68 is formed over first frozenlayer 64, with second frozen material layer 68 effectively forming aclean surface over the surface of first frozen material layer 64. FIG. 5also shows a second substrate 70 held by substrate holder 54. Secondsubstrate 70 has a surface 72 which contacts second frozen materiallayer 68, and which can be cleaned with treatment apparatus 52 byspinning bristles 56 relative to surface 72.

[0043] Frozen material 68 can be formed by providing a liquid over firstfrozen material 64 while cooling first frozen material 64 to atemperature below the freezing temperature of the liquid.

[0044] In particular aspects of the invention, a plurality of substratescan be cleaned with first frozen material 64, before provision of secondfrozen material 68. For instance, apparatus 50 can be configured toclean a set of five substrates with first frozen material 64.Subsequently, second frozen material 68 can be provided over firstfrozen material 64 and apparatus 50 utilized to clean another set offive substrates. Accordingly, frozen material is provided over bristles56 at periodic intervals during treatment of a plurality of substrates.Further, at specific periods of the cleaning of the substrates, thefrozen materials formed over bristles 56 can be melted from thebristles, and replaced with a new starting frozen layer, and the processrepeated. In the exemplary application described above wherein a newfrozen layer is formed at a period corresponding to the treatment offive substrates, an entirety of the frozen layers formed over bristles56 could be melted from the bristles after every 25 wafers, and a freshbuildup of frozen materials initiated over the bristles. Further, thefrozen materials removed from the bristles could be melted and purified,and subsequently re-frozen on the bristles.

[0045] Although the treating member 52 described above with reference toFIGS. 3-5 is described as a brush, it is to be understood that suchtreating member could comprise other forms, such as, for example, a pad.Preferably, the frozen materials described above with reference to FIGS.3-5 are formed at portions of the treating member which contact asurface of a substrate which is to be cleaned. Accordingly, if thetreating member is a pad, the frozen materials will be probably beformed at a surface of the pad which enables the frozen materials tocontact a surface which is to be cleaned.

[0046] In further aspects of the invention described above withreference to FIGS. 3-5, the frozen materials formed over the bristles ofcleaning member 52 can be at least partially melted as such bristles aremoved relative to a substrate. In such applications, the frozen materialundergoes a phase-change from a frozen state of matter to a liquid stateof matter during a cleaning process. Such can be advantageous forflushing contaminants from a surface of a substrate during cleaning withthe cleaning member 52.

[0047] Although the removal of frozen material from over cleaning member52 is described with reference to FIGS. 3-5 as comprising melting orscraping on the material, it is to be understood that in otherembodiments the frozen material can be removed by subliming the 7material. In such other embodiments, contaminants released from thesublimed material can be collected prior to utilizing cleaning member 52on subsequent substrates.

[0048] The embodiment described with reference to FIGS. 3-5 utilized acleaning member 52 to cleaning only one of two opposing surfaces ofsubstrate 70. FIG. 6 shows an apparatus similar to that described withreference to FIGS. 3-5, but configured to clean a pair of opposingsurfaces of substrate 70. The apparatus of FIG. 6 is shown at aprocessing step similar to that of FIG. 5, and numbering identical tothat utilized in describing FIG. 5 is used for FIG. 6. A differencebetween the FIG. 6 apparatus and that of FIG. 5 is that substrate holder54 (FIG. 5) is not visible in the FIG. 6 embodiment. If the substrateholder 54 of FIG. 5 were utilized in the apparatus of FIG. 6, such couldblock one of the cleaning members from contacting a surface of thesubstrate. Instead of such substrate holder, the FIG. 6 apparatus canutilize, for example, a substrate holder that retains substrate 70 atits edges (not shown).

[0049] Another embodiment of the present invention is described withreference to FIG. 7, wherein a cleaning apparatus 100 is illustrated.Cleaning apparatus 100 comprises a substrate holder 102, which isillustrated holding a substrate 104. Substrate 104 can comprise, forexample, a semiconductive material wafer, such as, for example, a waferof monocrystalline silicon.

[0050] Apparatus 100 further comprises a liquid/solid ejection system110. System 110 comprises a first tube 112 having an inlet 114 and anoutlet 116. A liquid 118 is flowed into tube 110 through inlet 114, andout of tube 110 through outlet 116. Outlet 116 is smaller than inlet118. Accordingly, liquid flows out of outlet 116 at a greater pressurethan it flows into inlet 114. The higher pressure liquid is ejected ontoa surface 105 of substrate 104 to clean such surface.

[0051] Device 110 further comprises a second tube 120 having an inlet122 and an outlet 124. Tube 120 flows through a chamber 126 configuredto convert a liquid-state material to a solid-state material. Chamber126 can comprise, for example, a region wherein one or both of atemperature and a pressure of a flowing liquid is changed to convert theflowing liquid to a flowing plurality of frozen particles.

[0052] A liquid 130 flows into tube 120 and through chamber 126, and isconverted to solid particles 132. Solid particles 132 are preferablyrelatively fine particles, and can be referred to as a “snow”. Solidparticles 132 are dispersed within the liquid 118 flowing through tube112, and are accordingly ejected from outlet 116 with liquid 118.

[0053] The ejected solid particles and liquid can clean surface 105. Thesolid particles can provide mechanical force against substrate surface105 which displaces contaminants from substrate surface 105, and theliquid 118 flowing across surface 105 can sweep the displacedcontaminants off of the surface.

[0054] In particular applications, liquid 118 and solid particles 132comprise CO₂. Accordingly, the liquid and solid convert to a gas uponwarming of substrate 104 to room temperature. In other embodiments,liquid 118 and solid 132 can both comprise H₂O. In yet otherembodiments, liquid 118 can comprise a different material than that ofsolid 132. For instance, liquid 118 can comprise glycol and solid 132can comprise H₂O. As another example, liquid 118 can comprise water andsolid 132 can comprise CO₂. In one aspect, liquid 118 and frozenparticles 132 can be referred to as a mixture flowed out of tube 112 andacross surface 105 of substrate 104.

[0055] Although frozen particles 132 are described as being formed witha chamber 126, other methods of forming frozen particles are encompassedby the present invention. For instance a method of forming the frozenparticles within a liquid, instead of utilizing chamber 126, is toutilize a second liquid 130 which freezes at a higher temperature thanfirst liquid 112. First liquid 112 is cooled to below the freezingtemperature of second liquid 130, and second liquid 130 is injecteddirectly into the cooled first liquid 112 whereupon the second liquidfreezes to form particulates of frozen material. Exemplary liquids forutilization in this aspect of the invention are glycol and H₂O, whereinthe H₂O freezes at a higher temperature than does glycol.

[0056] The apparatus of FIG. 7 moves a mixture of frozen and liquidmaterial relative to a substrate surface by flowing the mixture acrossthe substrate surface. FIG. 8 illustrates an aspect of the presentinvention wherein a similar effect is accomplished by submerging asubstrate 150 within a mixture 160 of frozen and liquid materials (thefrozen and liquid materials of mixture 160 can be the same as thosedescribed above with reference to FIG. 7), and agitating the mixture.Such agitation can rub frozen material across surfaces of the substrateto clean such surfaces. Substrate 150 can comprise, for example, asemiconductive material wafer. The agitation can be accomplished by, forexample, stirring the mixture and/or moving substrate 150. Althoughsubstrate 150 is shown resting on the bottom of a vessel in FIG. 8, itis to be understood that substrate 150 could be supported off of thebottom of the vessel with a holder (not shown).

[0057] It is noted that among the advantages of utilizing frozenmaterials for cleaning in accordance with the present invention is thatsurface properties of such materials can be changed with chemical orthermal modifications. Accordingly, a surface of a frozen material canbe made softer, or harder, for particular applications by modifying oneor both of a temperature of the frozen material surface or a chemicalcomposition of the surface.

[0058] In compliance with the statute, the invention has been describedin language more or less specific as to structural and methodicalfeatures. It is to be understood, however, that the invention is notlimited to the specific features shown and described, since the meansherein disclosed comprise preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A method of treating a surface of a semiconductor substratecomprising: providing a mixture comprising at least a frozen firstmaterial and a liquid second material on a surface of the semiconductorsubstrate; and moving the mixture relative to the substrate.
 2. Themethod of claim 1 further comprising: forming the mixture by providingthe frozen first material in a flowing stream of the liquid secondmaterial; and wherein the moving the mixture comprises flowing thestream with the frozen material therein across the surface of thesubstrate.
 3. The method of claim 2 wherein: the first materialcomprises CO₂, and wherein the frozen first material is formed bychanging one or both of the pressure and the temperature of a flowingliquid stream of CO₂ to form a plurality of frozen CO₂ particles; theliquid second material comprises liquid CO₂; and the mixture is formedby combining the frozen CO₂ particles with the liquid CO₂.
 4. The methodof claim 2 wherein: the first material comprises CO₂, and wherein thefrozen first material is formed by changing one or both of the pressureand the temperature of a flowing liquid stream of CO₂ to form aplurality of frozen CO₂ particles; the liquid second material comprisesliquid H₂O; and the mixture is formed by combining the frozen CO₂particles with the liquid H₂O.
 5. The method of claim 1 wherein themixture is provided on the surface of the substrate by submerging thesubstrate in a bath of the mixture; and wherein the moving the mixturerelative to the substrate comprises agitating the mixture.
 6. The methodof claim 1 further comprising: providing a treating member proximate thesurface of the substrate; and wherein the moving the mixture comprisespushing the mixture with the treating member.
 7. The method of claim 1wherein the first material is different than the second material.
 8. Themethod of claim 1 wherein the first material comprises CO₂ and thesecond material comprises H₂O.
 9. The method of claim 1 wherein thefirst material is the same as the second material.
 10. The method ofclaim 1 wherein the first material and the second material are both CO₂.11. The method of claim 1 wherein the first material and the secondmaterial are both H₂O.
 12. A method of treating a surface of asemiconductor substrate, comprising: providing a treating memberproximate a semiconductor substrate; providing a mixture at least afrozen first material and a liquid second material between a surface ofthe treating member and a surface of the substrate; after providing themixture, moving the treating member relative to the surface of thesubstrate; and melting or subliming the frozen first material to convertthe first material from a solid state of matter to another state ofmatter.
 13. The method of claim 12 wherein the first material isdifferent than the second material.
 14. The method of claim 12 whereinthe first material is the same as the second material.
 15. The method ofclaim 12 wherein the first material and the second material are bothCO₂.
 16. The method of claim 12 wherein the first material and thesecond material are both H₂O.
 17. The method of claim 12 wherein thesubstrate comprises a semiconductive material wafer, and wherein thetreating of the substrate occurs during or after subjecting thesubstrate to chemical-mechanical polishing conditions.
 18. The method ofclaim 12 wherein the treating member comprises a brush or a pad.
 19. Themethod of claim 12 wherein the treating comprises at least one ofcleaning and polishing the surface of the substrate.
 20. The method ofclaim 12 further comprising forming the mixture, the forming the mixturecomprising: providing a liquid blend of first material and secondmaterial, the first material having a higher freezing point than thesecond material; and cooling the liquid blend to a temperature whichfreezes the first material while leaving the second material as aliquid.
 21. A method of treating a surface of a semiconductive materialwafer, comprising: providing a treating member having a substantiallyplanar surface; forming a layer of frozen material over thesubstantially planar surface of the treating member; contacting asurface of the semiconductive material wafer with the layer of frozenmaterial, the surface of the semiconductive material wafer having aperipheral edge extending around it, the treating member substantiallyplanar surface extending beyond the outer peripheral edge on all sidesof the surface of the semiconductive material wafer; and moving at leastone of the treating member and the wafer relative to the other of thetreating member and the wafer.
 22. The method of claim 21 wherein thelayer of frozen material comprises H₂O.
 23. The method of claim 21further comprising, after the moving, removing the layer of frozenmaterial from over the treating member surface.
 24. The method of claim21 further comprising, after the moving, melting the frozen material andsubjecting the melted material to a purification process.
 25. A methodof treating a plurality of substrates, comprising: providing a treatingmember proximate a first substrate; forming an initial layer of frozenmaterial over a surface of the treating member; treating a surface ofthe first substrate by moving the treating member having the initiallayer of frozen material thereon relative to the surface of the firstsubstrate; after treating the surface of the first substrate, removingthe initial layer of frozen material from over the surface of thetreating member; after removing the initial layer of frozen material,providing the treating member proximate an other substrate; and treatinga surface of the other substrate by moving the treating member relativeto the surface of said other substrate.
 26. The method of claim 25wherein a plurality of additional substrates are have surfaces which aretreated with the treating member after the surface of the firstsubstrate is treated and before the surface of said other substrate istreated, the initial layer of frozen material remaining over a surfaceof the treating member during the treating of the surfaces of saidplurality of additional substrates.
 27. The method of claim 26 whereinone or more additional layers of frozen material are formed over theinitial layer of frozen material after the surface of the firstsubstrate is treated and before at least some of the surfaces of saidadditional substrates are treated.
 28. The method of claim 25 whereinthe initial layer of frozen material is formed over the treating memberby providing liquid material between the first substrate and thetreating member and subsequently freezing the material onto a surface ofthe treating member.
 29. The method of claim 28 wherein the freezingoccurs during or after the moving the treating member relative to thefirst substrate.
 30. The method of claim 25 wherein the removing theinitial layer of frozen material comprises melting the material from thesurface of the treating member.
 31. The method of claim 25 wherein theremoving the initial layer of frozen material comprises mechanicallyremoving the material from the surface of the treating member.
 32. Themethod of claim 25 wherein the removing the initial layer of frozenmaterial comprises scraping the material from the surface of thetreating member.
 33. The method of claim 25 further comprising: meltingthe initial layer of frozen material, subjecting the melted material topurification conditions; and re-freezing the material onto the treatingmember before treating the other substrate.
 34. The method of claim 33wherein the melting occurs during the removing of the material from thetreating member.
 35. The method of claim 33 wherein the melting occursafter the removing of the material from the treating member.
 36. Themethod of claim 33 wherein the frozen first material is filtered beforeit is re-frozen.
 37. The method of claim 25 wherein the materialcomprises CO₂.
 38. The method of claim 25 wherein the material comprisesH₂O.
 39. The method of claim 25 wherein the first substrate comprises asemiconductive material wafer, and wherein the surface of the firstsubstrate that is treated has an outer peripheral edge extending aroundit, the treating member comprising a substantially planar material thatextends beyond the outer peripheral edge on all sides of the surface.40. The method of claim 25 wherein the treating member comprises a brushor a pad.
 41. The method of claim 25 wherein at least some of theinitial layer of frozen material is melted as the treating member ismoved relative to the first substrate.
 42. A method of treating aplurality of substrates, comprising: providing a treating memberproximate a surface of first substrate; providing a frozen firstmaterial between a surface of the treating member and a surface of thefirst substrate; after providing the frozen first material, moving thetreating member relative to the surface of the first substrate; meltingthe first material; re-freezing the first material; providing thetreating member proximate a second substrate and providing the re-frozenfirst material between the second substrate and the treating member; andmoving the treating member relative to the surface of the secondsubstrate.
 43. The method of claim 42 wherein the first and secondsubstrates comprise monocrystalline silicon wafers, and wherein thetreating of the first and second substrates occurs after subjecting thefirst and second substrates to chemical-mechanical polishing conditions.44. The method of claim 42 wherein the providing the frozen firstmaterial between a surface of the treating member and a surface of thefirst substrate comprises freezing the first material on the surface ofthe treating member.
 45. The method of claim 42 wherein the providingthe frozen first material between a surface of the treating member and asurface of the first substrate comprises freezing the first material onthe surface of the first substrate.
 46. The method of claim 42 whereinthe first material comprises CO₂.
 47. The method of claim 42 wherein thefirst material comprises H₂O.
 48. The method of claim 42 wherein thetreating member comprises a brush.
 49. The method of claim 42 wherein atleast some of the first material is melted as the treating member ismoved relative to the first substrate.
 50. The method of claim 42wherein at least some of the first material is melted after the frozenfirst material is provided between the treating member and the firstsubstrate, and before the treating member is moved relative to the firstsubstrate.
 51. The method of claim 42 wherein at least some of the firstmaterial is melted after the treating member is moved relative to thefirst substrate.
 52. The method of claim 42 wherein the frozen firstmaterial is filtered before it is re-frozen.
 53. The method of claim 42wherein the frozen first material is provided between the surface of thefirst substrate and the surface of the treating member as a slurry in aliquid first material.
 54. The method of claim 42 wherein the frozenfirst material is provided between the surface of the first substrateand the surface of the treating member as a suspension in a liquidsecond material.
 55. A method of treating a plurality of substrates,comprising: providing a treating member proximate a first substrate;forming a first frozen material over a surface of the treating member;moving the treating member having the first frozen material thereonrelative to the surface of the first substrate; melting or subliming thefirst frozen material to change the first frozen material from a solidphase to another state of matter; forming a second frozen material overthe surface of the treating member; after forming the second frozenmaterial, providing the treating member proximate a second substrate;and moving the treating member having the second frozen material thereonrelative to the surface of the second substrate.
 56. The method of claim55 wherein the first frozen material and the second frozen materialcomprise the same material.
 57. The method of claim 55 wherein thesecond frozen material is formed over the first frozen material.
 58. Themethod of claim 55 wherein the first frozen material is removed fromover the treating member before the second frozen material is formedover the treating member.
 59. The method of claim 55 wherein the firstand second substrates comprise monocrystalline silicon wafers, andwherein the treating of the first and second substrates occurs aftersubjecting the first and second substrates to chemical-mechanicalpolishing conditions.
 60. The method of claim 55 wherein the firstfrozen material is removed from over the surface of the treating memberby melting the material of the first frozen material from the surface ofthe treating member.
 61. The method of claim 55 wherein the first frozenmaterial is removed from over the surface of the treating member bymechanically removing the first frozen material from the surface of thetreating member.
 62. The method of claim 55 wherein the first frozenmaterial is removed from over the surface of the treating member byscraping the first frozen material from the surface of the treatingmember.
 63. The method of claim 55 wherein the first frozen material ismelted to change the phase of the first frozen material, and furthercomprising: subjecting the melted material to purification conditions;and re-freezing the material onto the treating member to form the secondfrozen material.
 64. The method of claim 63 wherein the frozen firstmaterial is filtered before it is re-frozen.
 65. The method of claim 55wherein the material comprises CO₂.
 66. The method of claim 55 whereinthe material comprises H₂O.
 67. The method of claim 55 wherein thetreating member comprises a brush or pad.
 68. The method of claim 55wherein at least some of the first frozen material is melted as thetreating member is moved relative to the first substrate.
 69. A methodof treating a plurality of substrates, comprising: providing a firstmaterial between a surface of a treating member and a surface of asubstrate, at least some of the first material being in a form of afirst state of matter; after providing the first material, moving thetreating member relative to the surface of the first substrate; changingthe form of at least some of the first material from the first state ofmatter to a second state of matter; while the at least some of the firstmaterial is in the form of the second state of matter, subjecting thefirst material to a purification process; after the purificationprocess, changing the form of at least some of the first material fromthe second state of matter back to the first state of matter; afterchanging the form of at least some of the first material back to thefirst state of matter, providing the treating member proximate a secondsubstrate and providing at least some of the first material that hasbeen changed back to the first state of matter between the secondsubstrate and the treating member; and moving the treating memberrelative to the surface of the second substrate.
 70. The method of claim69 wherein the phase change of the first material from the first stateof matter to the second state of matter is accomplished by subjectingthe first material to one or both of a change in temperature and achange in pressure.
 71. The method of claim 69 wherein the phase changeof the first material from the second state of matter to the first stateof matter is accomplished by subjecting the first material to one orboth of a change in temperature and a change in pressure.
 72. The methodof claim 69 wherein the first state of matter is solid and wherein thesolid first material is provided between the surface of the firstsubstrate and the surface of the treating member as a slurry in a liquidfirst material.
 73. The method of claim 69 wherein the first state ofmatter is solid, and wherein the solid first material is providedbetween the surface of the first substrate and the surface of thetreating member as a suspension in a liquid second material.
 74. Themethod of claim 73 further comprising forming the suspension, theforming the suspension comprising: providing a liquid mixture of firstmaterial and second material, the first material having a higherfreezing point than the second material; and cooling the liquid mixtureto a temperature which freezes the first material while leaving thesecond material as a liquid.
 75. The method of claim 73 wherein thefirst material comprises H₂O and the second material comprises glycol.76. The method of claim 73 wherein the first material comprises CO₂ andthe second material comprises H₂O.
 77. The method of claim 69 whereinthe first state of matter is solid and the second state of matter isliquid.
 78. The method of claim 69 wherein the first material comprisesCO₂.
 79. The method of claim 69 wherein the first material comprisesH₂O.
 80. The method of claim 69 wherein the first material comprisesCO₂, and wherein the first state of matter is solid and the second stateof matter is liquid.
 81. The method of claim 69 wherein the firstmaterial comprises H₂O, and wherein the first state of matter is solidand the second state of matter is liquid.
 82. The method of claim 69wherein the treating member comprises a brush or a pad.